Glacier Mass Balance: equilibrium or disequilibrium response?

I get asked at least once a day about the future prognosis for alpine glaciers and whether they have a future. I will focus here on North American glaciers whose mass balance measurements in the West from 1984-2005 indicate a declining trend. The trend suggests that all of the glaciers are out of balance and that some will disappear. The question is determining which glaciers are merely out of equilibrium and can retreat to a position of equilibrium, and which are in complete disequilibrium and will melt away? Let me explain.

Glaciers have long been recognised as sensitive and reliable indicators of climate. This together with their wide distribution has made them a key marker of current climate change. The World Glacier Monitoring Service (WGMS) collects from alpine glaciers around the world annual mass balance data, which is the difference between annual accumulation and annual ablation (from melting and sublimation). A glacier is divided into an ablation zone where all accumulated snow is lost from the winter and an accumulation zone where snowpack is retained to the end of the summer. The alpine glaciers discussed here are not calving, nor do they have superimposed ice, two factors that complicate measurement. For an alpine glacier to have an equilibrium balance it typically must have upwards of 60% of its area in the accumulation zone at the end of the summer melt season.

Glaciers respond to climate change in an attempt to achieve a new equilibrium. A glacier advances due to a climate cooling/snowfall increase that causes positive mass balance. The advance increases the glaciers area at low elevation where ablation is highest, returning the glacier to equilibrium. A climate warming/snowfall decrease leads to negative mass balances and glacier retreat. An equilibrium response occurs when a new equilibrium is reached by a retreating glacier losing enough of its high ablating sections, usually at its lowest elevations, so that accumulation once again balances ablation. This is a glacier equivalent to jettisoning bad debt. If a glacier cannot retreat to a point where equilibrium is established, it is in disequilibrium with the current climate. A glacier that is in disequilibrium will melt away with a continuation of the current climate.

Therefore, it is important to note whether glaciers are undergoing an equilibrium or disequilibrium response to climate change. It was noted in the Tropical Glacier Retreat post that if the annual equilibrium line rises above the mountain top this will lead to glacier loss. The equilibrium line is the elevation on a glacier at which annual accumulation equals ablation. This is not the only means to an end for a glacier, nor is it a robust means for identifying glacier disequilibrium. A glacier that is approaching equilibrium during retreat will thin mostly near the terminus, and at some elevation above the terminus, usually near the equilibrium line or in the lower accumulation zone, there will be comparatively little thinning (Schwitter and Raymond, 1993). This indicates that at least a portion of the glacier is healthy. A glacier that is not approaching equilibrium will thin appreciably along the entire length of the glacier (Pelto, 2006). There are two means to identify glacier disequilibrium. The first is substantial thinning along entire longitudinal profile of the glacier. The second is frequent years with no accumulation area at all – that is, the equilibrium line is above the glacier.

Annual mass balance measurements over at least 20 years are available on 16 glaciers in North America which are submitted to the WGMS. The annual balance and cumulative balance records of these glaciers illustrate the adjustment of these glaciers to climate change from 1984-2005 (Figure 1-2). The annual balance record, in meters of water equivalent, 1984-2005 indicates that despite continued significant retreat of all 16 glaciers, mass balances are declining. The mean annual mass balance has declined from -0.35 m/a 1984-1990, to -0.59 m/a in 1991-1997, to -0.91 m/a from 1998-2005. Instead of approaching equilibrium after several decades of dominantly negative annual balance, and significant retreat, mass balance is becoming more negative. This indicates the glaciers are getting further away from equilibrium, not approaching it. The consistency of the cumulative balance trends further indicates the glaciers mass balance record is dominated by large scale regional to global climate change.

Which glaciers are experiencing an equilibrium response? Glacier thinning in the accumulation zone is limited on Lemon Creek (Miller and Pelto, 1999), Gulkana and Wolverine (Sapiano, et. al, 1998), and Easton, Lynch and Rainbow Glacier (Pelto, 2006). Each appears able to retreat to a new point of equilibrium with the current climate. On Columbia, Daniels, Foss, Ice Worm, Lower Curtis, Sholes, and Yawning Glacier thinning is not notably less in the accumulation zone than the ablation zone, indicating disequilibrium (Pelto, 2006). Two North Cascade glaciers where mass balance measurements were conducted the Spider and the Lewis Glacier disappeared during this interval (Pelto, 2006). On Helm and Place Glacier the loss of more than 20% of their entire volume, since 1984 suggest they too are in disequilibrium. South Cascade Glacier has lost 70% of its volume since 1890 (Josberger et al., 2006), and is still experiencing large negative balances indicating disequilibrium. In Glacier National Park, North Cascades, Helm Glacier and Place Glacier frequent loss of the entire snowcover by the end of the ablation season has become commonplace (WGMS, 2005). The result is in net ablation throughout the accumulation area causing thinning of the glacier in the accumulation zone.

Are the glaciers responding primarily to climate changes of the last 30 years, or to the post Little Ice Age conditions? In the North Cascades Rainbow, Yawning, Easton and Lower Curtis Glacier all advanced during the 1950-1975. Sholes, Columbia, Ice Worm, did not advance or retreat significantly during this period. Thus, each of these glaciers is definitively responding to the climate of the last 30 years.

In the North Cascades the warmer temperatures have increased summer ablation on the glaciers (Pelto, 2006). The glaciers are losing mass not just because of increased summer melting. In the winter despite a small increase in precipitation, retained snowpack at the end of the winter has declined. The reduced accumulation is due to rain and melt events in the winter. On Lemon Creek Glacier it has been noted that fewer ice lenses are forming (Miller and Pelto, 1999). This is an indication that the spring snowpack is not cold enough to lead to substantial refreezing of meltwater. This is important information regarding the 1998 mass balance, because 7-11% of the retained annual accumulation is typically in ice lenses. Failure to retain this meltwater increases net ablation. The reason for the change is warmer snowpack winter temperatures, +4oC above the long term mean at the Juneau Airport seven miles from the glacier at sea level in 1997 and 1998. The result of the failure to recapture meltwater as internal accumulation is increased ablation and negative annual balances (Kaser and Osmaston, 2002).

Alpine glaciers are losing income during the winter (snowpack) and have increased expenses (ablation) in the summer, and there is no financial safety net for recovery. In the North Cascades of Washington the United States Geologic Survey (led by Austin Post) completed an inventory identifying 756 glaciers in the range based on photographs from the 1950’s and early 1960’s. In 2005 an examination of these same glaciers, indicates that at least 53 are no longer present, illustrated in google earth tour.

If we had an endangered glacier act, we would need to invoke it for alpine glaciers in many of our world’s glaciated mountain ranges.

Interesting! From Figure 2 it seems that from 1995 to 2002 all the glaciers were stable. Prior to that, there were three glaciers shrinking at the rate of 1.5 mwe per year. The others shrank at an average of 0.4 mwe per year. Since 2002 they have all been shrinking a rate of 1.5 mwe per year. That seems to imply that the faster decline rate characteristic of the southern glaciers of BC is now affecting the northern glaciers of Canada and Alaska.

Mauri, you wrote “The question is determining which glaciers are merely out of equilibrium and can retreat to a position of equilibrium, and which are in complete disequilibrium and will melt away?” Could it be those which were declining at the rate of 0.4 mwe per year were retreating to a new position of equilibrium, but that now all are in complete disequilibrium and will melting completely away at 1.5 mwe per year?

This is a good introduction to the dynamics of continental glaciers. However, the concept of mass balance is used without ever defining what it means and how it is measured. I would like to know what a value such as -0.35 m/a actually represents.

From what I understand, 80-90% of all world glaciers are in retreat. In the case of Greenland, where glaciers are experience an increasing number of icequakes each year, they are currently expecting that most of it will be gone in time, but there will be a small dome towards the center, assuming that global warming doesn’t get considerably worse. Then there are a few glaciers in the world (places like Greenland) where glaciers are currently in advance due to increased precipitation.

According to Hansen, the most important time of ice loss is during the spring, not summer: ice melt at this time of the results in dark puddles which will resulting in higher summer melts and annual ice loss.

One good place to send people for further infomation in this area is “State of the Cryosphere” at:

Sorry – you had brought up Google Earth already, and right at the end of the post where I would normally have seen it if I had been typing while at Real Climate.

Morning commute.

When I am on the bus, I will often try working on my posts offline in Notepad or GMail, just in case, as either a backup or what have you. In any case, the neat thing about Google Earth is that people and various organizations will be able to add their own pictures. Fish harvests giving way to unintended jellyfish catches off of Japan, algae blooms and dead zones off of the coast of Oregon, etc.. Then it will be made available to anyone with an internet connection.

It appears to me that the pictures of the Lower Curtis Glacier don’t show the same region, as the ridge shown in the top center of the 1908 picture is over on the extreme right of the 2003 photo (cut off, actually). Therefore, it’s sort of hard to judge how much change there was. Maybe some recropping would be useful.

Shifting the line of equilibrium reminds me of the discussion a while back about “loading the weather dice” as this relates to shifts in probabilities of certain kinds of weather. So while glaciers might indeed be getting snow, and in any given year might get a lot or little, it’s not the presence or absence of precipitation that matters as much as the overall forces influencing the balance of the accumulation of same.

Like a gambler that wins a few and loses a few, but against whom the overall odds are in favor of long term loss. Everyone knows the odds favor the house, but we don’t usually know by how much. We also “know” that AGW is going to favor melting, but we don’t know by how much and rare “wins” in the accumulation areas of glaciers can fool us into the same kind of wishful thinking nonprofessional gamblers succumb to, that if we just keep playing we’ll get lucky.

Are the glaciers responding primarily to climate changes of the last 30 years, or to the post Little Ice Age conditions? In the North Cascades Rainbow, Yawning, Easton and Lower Curtis Glacier all advanced during the 1950-1975. Sholes, Columbia, Ice Worm, did not advance or retreat significantly during this period. Thus, each of these glaciers is definitively responding to the climate of the last 30 years.

With so many glaciers worldwide how do we know that this isn’t just a regional change? The average skeptic will claim cherry picking. Also, your graphs don’t go back to 1950. What is your source?

How important is it really for the prognosis of the patients whether the glaciers are in equilibrium or disequilibrium with the current climate? The current climate is not going to stay – it is just a passing moment in time. Climate is warming up and will continue to do so. So isn’t the question: how many glaciers are going to survive a global warming by 2 ºC, or by 3 ºC or 4 ºC above preindustrial temperatures?

It has maps, top-level summaries (sortable by various fields), a next-level page per glacier with pictures/graphs, and then the actual data for each, generally starting in 1893. I really like the presentation because both graphs, summaries, and the raw data are all provided.

Also, the following is an interesting paper on longer history of several Swiss glaciers, including the longest one, the Great Aletsch, since there are longer historical records of various kinds:

Re: #3, “Mass balance” as a measurement means the change in the average thickness of the glacier after correcting for variations in the density of the snow/ice. A value of -0.35 m/a means that averaged over its whole surface area the glacier is effectively thinning at a rate of 0.35 meters per year (“a” is for “annum”). Depending on context it may be expressed as meters water equivalent (mwe) or meters ice equivalent, but in each case the scientist making the measurement attempts to avoid the different densities of snow and ice by expressing everything in terms of the thickness that would be seen if all the material were fully compressed.

The typical technique for measuring changes in mass balance is for scientists to stake out regions on the surface of the glacier with deeply anchored reference points and measure the change in effective thickness year to year. For example, each year a short core might be drilled to the marked reference level and the contents of that core melted to determine the water equivalent thickness. Such work is rather labor intensive since an adequate measurement really requires that the work be done at many different sites scattered across the surface of the glacier.

Mass balance doesn’t explicitly track changes in glacier terminus or calving from glaciers that terminate in water. For this reason it is most useful for glaciers where the total glaciated volume is much larger than the terminus region.

For the curious, here is a 50 year record of changes in mass balance based on the global compilation of Dyurgerov and Meier.

“bjc” above, citeing a paper, states a belief that icequakes in Greenland “… appear to be localized to NW Greenland glacier complexes and there is no apparent increase in other Greenland glacier complexes.”

I read it. That’s not accurate.

bjc, where did you get your belief that you wrote above?
Are you quoting someone else’s opinion about what the paper says?
Why do you believe the icequakes “appear to be localized to NW Greenland”?

The paper describes them all around the coast. The paper describes them as increasing where the Arctic sea ice has melted, and that happened later further north.

Figure 3 shows the locations. You can look this up. As the Arctic sea ice has melted, the number of quakes increased.
That has happened more recently further north (“NWG”). It happened a bit earlier further south and east, e.g. region K.

“Other temporal trends exist but are not as compelling due to the small number of events. …. This increase in
northerly extent correlates well with the decrease in southerly extent of arctic sea ice [Walsh and
Chapman, 2001; Stroeve et al., 2005] and is suggestive of a common cause.”

“… Some regions (e.g., region K) are consistent with a constant number of events per year whereas other regions (e.g., region NWG) have had an unmistakable dramatic increase during the same time period. Glacial earthquakes in region K are larger on average than in any other region, with these events comprising all of the events larger than 0.9Ã�1014 kg m. …”

Seriously — did you get your stated belief from someone else’s opinion, or from the actual text and map?
I’m always very curious when people make statements and give references, and I look them up and they don’t appear correct, how you got your understanding.

With respect to #2 if a glacier has a mass loss of -1.5 m/a year after year that is a good sign that it is seriously out of equilibrium. Yet, if it is a large glacier and a section remains reliably snowcovered the glacier could still retreat to a point of equilibrium.

With respect to #4, plenty of posts in Realclimate focus on Greenland, but the topic here is not an ice sheet, but small alpine glaciers. An important point, is that we can see that many of the glaciers are in disequilibrium. We do not need to estimate the future.

On #7 I will more exactly reproduce the picture when I visit the Lower Curtis Glacier this summer, 99 years after the previous picture. Focus on the terminus area and the change is evident.

On #9 since I have included every glacier with reliable data in North America I have not cherry picked. This is a regional focus, though if you look at the cumulative balance of the WMGS for the globe you will see an almost identical graph. I do not go back to 1950 because mass balance was measured on only one glacier that year. In terms of continuous measurements only two Lemon Creek and South Cascade were begun in the 1950’s. The source of the data is the WGMS for all but Lemon Creek Glacier. All of the mass balance data has been published for these glaciers. I measure the North Cascade glaciers except for South Cascade Glacier.

#15 The Swiss site is excellent. No other nation can match their program from annual terminus position measurement. The trends seen their are similar to the North Cascades. The glaciers are somewhat larger, with higher elevation accumulation zones with respect to the termini,and as a result with current climate more should be able to retreat to a new point of equilibrium.

With respect to #9 I am only focussing on a region, I am not trying to make a global statement. Since I have utilized data from every glacier with consistent reliable data in western North America, cherry picking did not occur. I focus on this region, becuase I measure the mass balance of 11 of theses glaciers, it is what I know. We too often hear second hand about what is observed. I thought it important to share first hand observations and explanations. In 1950 only one glacier in North America was assessed for mass balance, and that glacier is not reported here. By 1960 measurements had begun on Lemon Creek and South Cascade glacier.

The link in #16 illustrates the similar cumulative mass balance trend for the globe to Western North America.

The Swiss as noted in #15 have the best alpine glacier monitoring program of any nation. There annual terminus surveys provide an amazing data set. In 2006 it was 84 retreating, and one advancing, cherry pick that.

A good example of a glacier that will be more resilent to current climate change is Glacier du Brenay. Note in this picture the low elevation terminus lacking crevassing and looking stagnant. The Brenay will lose this section of the glacier with present climate. however, then there is an icefall separating the terminus-from the accumulation area. This helps separate the glacier dynamically and also means the accumulation zone is that much higher versus the remainder of the glacier, making this glacier more likely to survive. Brenay. Compare this to the Foss Glacier Foss

To the author: Is there any information on the latitude of the glaciers studied here? Is there any relationship between latitude and which glaciers are and are not in equilibrium?

Global Climate Change happens on a global scale, but not homogeneously. The higher the latitude, the more drastic the effect, meaning the polar regions should experience a more drastic overall temperature increase than the equatorial regions. I am wondering if this is found in any of the evidence quoted above.

In response to #3 and #4: It is important to understand the difference between the 2 types of glaciers in the world. Alpine glaciers, being discussed here, are glaciers located in mountainous regions such as the Cascades, the Alps (their namesake), and others. These glaciers operate in a wholly different way than do Continental Glaciers which cover large areas of a continent such as Greenland or the Arctic regions.

Alpine glaciers are a great indicator of change as they are smaller in volume, and have the above mentioned ablation and accumulation zones, and equilibrium line, which we see shifting.

In response to #14: Relating Global Climate Change to Continental Drift as an argument against taking action on the issue is a poor argument. Continental drift is a natural process which has literally been going on since the creation of Earth (however you believe this happened). Earth’s current observed climate changes are most definitely manmade.

Re: #3, “Mass balance” as a measurement means the change in the average thickness of the glacier after correcting for variations in the density of the snow/ice. A value of -0.35 m/a means that averaged over its whole surface area the glacier is effectively thinning at a rate of 0.35 meters per year (“a” is for “annum”). Depending on context it may be expressed as meters water equivalent (mwe) or meters ice equivalent, but in each case the scientist making the measurement attempts to avoid the different densities of snow and ice by expressing everything in terms of the thickness that would be seen if all the material were fully compressed.

Thank you for the explanation.

This was something I often wondered about, especially with new ice or snow. Obviously it would be less compact and would be far more susceptible to melt in the future. But I suppose the water-equivilent in the essay should have been a dead give-away.

Agatha you might expect a latitudinal gradient since it is often noted that warming has been more substantial at the poles. However, in this data set the two glaciers with the poorest mass balance are in BC in the middle latitudinally, the third poorest mass balance glacier is the South Cascade one of the more southerly glaciers. The trend globally is not decreasing mass balances at higher latitude in the WGMS data set either. One reason may be exemplified by Norway where a series of warm wet winters in the late eighties early nineties led to positive mass balances for many of their glaciers.

Hank:
Check the data. I did examine the data fairly closely. I am not relying on someone else and it is kind of rude to argue otherwise without first asking the question in a more polite or at least circumspect manner.

More specifically if you look at both the Science paper and the Harvard Working Paper you will see the following:

The Science article and Harvard AGQ paper indicate the following geographic distribution of glacial events:

I do not understand the reason for the difference in these numbers between the two papers but that does not bear on the major point at issue.

The Science article goes on to note that ” a part of the increase in the number of glacial quakes is due to the occurrence of more than two dozen of these quakes in 2000 to 2005 at the northwest Greenland glaciers, where only one event (in 1995) had previously been observed.” (p1757)

Now Tsai and Ekstrom also say in the earlier paper:
“Some regions (e.g., region K) are consistent with a constant number of events per year (emphasis added) whereas other regions (e.g., region NWG) have had an unmistakable dramatic increase during the same time period.”page 10 Analysis of Glacial Quakes. You use the same quotation but apparently did not check to see just how many quakes occurred in the NWG and RI glacier complexes. I did and the authors statement is IMHO misleading.

NWG and RI glacier complexes account for 43 of 182 or 27 of 136. The net increase in earthquakes from 2000 to 2005 is 51 out of a total of 182. Obviously if all but one of the 43 NWG/RI GQs occurred in this period we have the overwhelming percentage (42 of 51 or 80%) of the increase coming from 2 glacier complexes in Greenland. If this is true, then the numbers are such that whatever seems to be happening is not a Greenland event but a Northwest Greenland event and should be interpreted as such.

Do you interpret these data differently? If not, I accept your apology.

I think that may be debatable. I mean, the core had to segregate from the crust before the continents could drift. So I suppose it depends, at which stage would you consider the earth to be created? Now with respect to climate, well that just refers to whatever is going on in various locales on the planet’s surface. Heck, we even speak of climate, and weather, on the gas giants, where the actual surface might be rather nebulous. I’d have to say that climate change on earth precedes continental drift.

Not only glaciers are retreating, frost lines are retreating as well. When antarctica becomes snow free and habitable, which country will claim it for its own? Sick people either get better, or die. What lies ahead for this very sick earth?

Lets see how this works. Timothy shows enthusiasm for glaciers and interest in their retreat. bjc then responds with an attempted neutralizing comment, nit picking a breadcrumb regarding the increase frequency of earth tremors induced by moving glaciers. Cohort or dobbleganger “Harry” then chimes in with a snarky remark regarding Stefan’s pronouncement about climate change. Hank pounces on bjc for the neutralizing comment. bjc defends the neutralizing comment with interpretations resembling squid ink. bjc, feeling cocky, then asks when Antarctica will be habitable. Could bjc perhaps be with the Competitive Enterprise Institute? CEI.. now that is a choice piece of truth speak for you. Not much competitive about rebuilding the oil monopolies now, is there?
Just a bit of attempted humor for a beautiful, WARM, Saturday morning!

Note the comments don’t appear as they are made, they end up in timestamp order but may not appear that way for a day or two if the hosts are busy; some pass the automatic filters, some get reviewed faster. The whole Greenland digression is as Dr. Pielto noted early on covered in other topics. My apology to Dr. Pielto; I’ll follow that up elsewhere if there’s news. My posting was made before I saw this:

>plenty of posts in Realclimate focus on Greenland, but the topic here is not an ice sheet, but small alpine glaciers.

Skeptic Tracker:
I assume to justify your comments you have read both Ekstrom papers and have a point of view regarding their findings? But then if you had read them, my comments would look less like “squid ink”. Hank, at least, had made the effort to read them.

Today’s Editor:
It is fair enough that you edited out parts of my last comment in response to Skeptic Tracker. However, I would have preferred it if Skeptic Tracker’s comments had been dealt with in a similar fashion and in accordance with your comment policy. Skeptic Tracker’s comments, left as written, are clearly an ad hominem and entirely without foundation, i.e., I have never had anything to do with any think tank or interest group. I had merely pointed out that an earlier assertion that Ekstrom’s Science paper on the recent increasing frequency of glacial quakes does not pertain to Greenland as a whole. 80% of the increase in these newly identified seismic events took place in two proximate glacier complexes in NW Greenland. I do not know whether this is a widely recognized fact or not – but given the visibility of a paper in Science I felt it was appropriate to point this out.
You have my email. If I have transgressed in some way, please let me know. I certainly prefer a civilized and respectful discussion forum.

I was wondering if Glaciers where ever considered as giant thermometers, in a real sense, with thermistors embedded in them as a way to determine temperature vs melting? There must be a critical core temperature not achieved after warm winters which should help accelerate melting.

bjc– you ignored the time sequence of events. Look back. Icequakes began in each area when the sea ice quit obstructing the outflowing ice. The process happened earlier on the southeast. Our hosts will open a topic when there’s new info, I trust. Endit.

I will be back in the field measuring mass balance this summer on 10 of the above glaciers. I have forecasted a negative balance year for them based on the Pacific Decadal Oscillatiion and the El Nino Southern Osciallation index values for the winter. I will also being mapping an area that just lost its glacier.

One problem with glaciers that is often picked up by the sceptics, is the behaviour of calving glaciers which is often out of phase with local climate. This allowed people like David Bellamy to cherry-pick calving glaciers from ice caps which weren’t particularly recessed, or were near their Neoglacial limits. This is a major problem in Patagonia where many glaciers on the western side of the icefields are tidewater calving, and those on the east side are lake-calving. Both behave differently.

I suppose the analysis was fun for you. I’m actually just a random contrarian, as opposed to a dogmatist. (Let’s make it illegal and have trials for people who disagree with us about climate change.) I don’t know those other folks, and they probably don’t want to know me.

I’m still fascinated by the concept that an increase in CO2 will lead to a decrease in the cooling effect of CO2 (supposedly emission to space). It makes me wonder what those models will show if all of the atmospheric CO2 is removed. Will that cause warming because there is no longer any CO2 present to radiate?

Obviously, this is way off topic. I would be mildly surprised if the glacier measurements in the main thread are incorrect. It certainly does appear that many glaciers are retreating. I freely admit, I couldn’t see any fun ways to poke at that, and being an avid contrarian, and more or less oblivious to anyone’s thoughts but my own, I had to strike out in a different direction.

If another 50 years go by, and no cooling cycle begins, I suppose I will have been incorrect. I’d be surprised, but willing to admit to being incorrect.

With respect to retreating glaciers, it appears to be a natural part of the temperature regulation system of the planet. It is quite nice sometimes to live on a planet that has three phases of water present on its surface and in its atmosphere. Given the tremendous non-equilibrium and continuously changing forces that set the rough dial of planetary temperature (sun, gravitational pull of other bodies, you can probably come up with a few more on your own), it is good that water can so facilely change phases to offset some of the more dramatic and unfriendly temperature changes that would occur otherwise. Water makes a great heat conveyor belt to transport energy around the globe, and up to the top of the troposphere when the surface warms. It can respond to dampen the effects of increased or decreased temperatures. This is really quite remarkable. Since there is no switch to turn it off when it’s done, oscillation is to be expected.

bjc,
Lighten up man or woman! I said this was an attempt at humor! As a matter of fact I did read the Tsai and Ekstrom paper at the link you provided, and I have a problem with your statement to Timothy, right off the bat. That paper clearly states that in region H “since 2000 there has been a significant increase to 10 or more events per year”. And region H is in southwest Greenland. So where do you come off saying that the increase is localized to the North West? The paper also states “A second temporal trend in the data is the dramatic increase in the total number of events since
2002, with more events detected in each successive year since 2002 and resulting in more than
twice as many events in 2005 as compared with any year prior to 2003.” So I will charitably suggest that perhaps you, bjc, did not read the article. BTW, when I had my first job in the business world with my new technical degree, many many years ago, my mentor dissected the word assume and explained why it was such a weak word to use. Didn’t anyone ever do that for you? Anyway, I stand by my squid ink analogy. It wasn’t an insult, just a frank statement of the type of defense of your position that you appeared to have used. Your statement about the localization of glacier quakes just seems off the wall, if you know what I mean. Kind of like re-arranging deck chairs on the Titanic. I hope you have grown a sense of humor since this morning! Cheers!!!

I’m still fascinated by the concept that an increase in CO2 will lead to a decrease in the cooling effect of CO2 (supposedly emission to space).

Good! Being fascinated by physics might actually motivate you to learn some!

With respect to retreating glaciers, it appears to be a natural part of the temperature regulation system of the planet. It is quite nice sometimes to live on a planet that has three phases of water present on its surface and in its atmosphere.

Oh lord, the anthropic principle so beloved of creationists visits climate science, though in a weakened form.

You are correct that region H (SE Greenland) had an increase in earthquakes notably in 2004 and 2005. Region NG in NW Greenland has also had an increase. Lumping region H with the other three Eastern Greenland complexes was a mistake on my part.
A closer look at the paper reveals that out of the 7 glacier complexes noted only these two regions had an actual noticeable increase in these quakes since 2000 compared to 1993 through 1999. Region H, accounts for an increase over expected number of 28 quakes for 2000 through 2005. Region NG accounts for 31 of the quakes. These two complexes account for all of the increase in frequency of glacial quakes.

If we take Greenland as a whole, the average number of quakes across the entire 7 complexes was 10 per year from 1993 through 2001. Given that there were a total of 92 quakes from 2002 through 2005, that leaves a net increase over past trends of 52. During this shorter period, Region H had an increase over trend of 29 and Region NG an increase over trend of 27. There was a slight decrease in the other 5 Regions.

So while you are correct that my original assertion that the increase was only in NW Greenland was wrong, the data still does not justify the assertion that the increase applies to all of Greenland. The original title of the Science article, Seasonality and Increasing Frequency of Greenland Glacial Earthquakes, is somewhat misleading.

Stephen good point on the calving glaciers. The North American mass balance data set here has no calving glaciers. Glacier dynamics is much more important to glacier behavior on calving glaciers. I missed #1, there is no global time series of the change in ice and glacier volume or area. We can begun one with the satellite era and an inventory has been completed by some nations for the 1970’s period. To get a better view of Lemon Creek Glacier and its neighbors take a look at the google earth tour showing change over the last 50 years at GE Tour, the file link is near the end of the first paragraph.

The book Glaciers by Hambrey & Alean (2004) has a table showing the distribution of glacierized area of the world (from World Glacier Montioring Service, 1989). It has 8 regions along with the area covered, but being it is 1989 data, it is kind of dated.

I would be interested in seeing more data of the Tibetan plateau glaciers since the rate of melt I see stated is like 7% a year. I have read the Yangtze river is likely to have a severe flood this year because of the melting.

It’s not as accessible as the Swiss site, but it’s clear that they are trying very hard, as well they might, because they have additional serious hydrology issues ahead, dwarfing the (very real) ones we have here in California.

I’ve done the Yangtze boat trip (Wuhan–>Chongqing, highly recommended, if you haven’t done it; at least a lot of that trip doesn’t have to deal with air pollution, but go soon). Wuhan: Imagine a giant New Orleans, (but without hurricanes, at least), many old levees, ~8M people, and criss-crossed by big flood-prone rivers.

The scale of efforts needed in dealing with *that* river are rather awesome, already, and let’s hope the Three Gorges Dam actually works, because Wuhan already has enough flooding problems: http://www.ehs.unu.edu/file.php?id=123.

“Highly individual and non-uniform changes in glacier geometry (disintegration) indicate a massive down-wasting rather than a dynamic response to a changed climate. Our results imply stronger ongoing glacier retreat than assumed so far and a probable further enhancement of glacier disintegration by positive feedbacks.”

It seems to me that skeptics don’t like discussing this topic, probably because it is such hard proof of global warming. They’d rather talk about icequakes in Greenland, apparently… Speaking of skeptics, it’s worth raising the issue of Kilimanjaro – a good discussion from National Geographic is here (2003). As some may recall, Pat Michaels tried to claim that Kilimanjaro’s alpine glacier retreat had nothing to do with global warming in 2002. The more reasonable explanation is that intensified convection over the Atlantic and Indian Oceans is altering the African monsoon and delivering less precipitation to the continent – which, in combination with rising surface temperatures, presents a double whammy to Africa.

The number of glaciers and glacier area reported in China is likely a reliable number, not that you can take it exactly as stated to the bank. However, the 6.5 m of ice thinning in the last 40 years, is not a dependable number at all. The Chinese did not have good maps of the surface elevations of the glaciers 40 years ago, nor have they measured the mass balance of even one glacier over a 40 year span. Thus, I guarantee you this number on thinning is worthless. In terms of excess glacier melting causing flooding. Glacier melting is not something that has huge spikes that tend to cause flooding. The loss of glaciers lead to led storage of spring snowmelt leading to more spring flood potential. But the rapid melt is not a cause of flooding anywhere, unless a glacier dammed lake is involved.

re: #48
Thanks for the calibration of numbers, I did wonder about 6.5 as well…

re: glacier melt: sorry for any ambiguity: I never meant to imply that glacier melt was causing the floods directly, it was more as an obvious indicator of changes in the local hydrology, which at least seemed likely to exacerbate the existing snowmelt pulse problems they already have. offhand, I can’t think of any reason why shrinking Himalayan glaciers would be very helpful to Asia.

FWIW, I believe that there is global warming and that glaciers as a result are retreating. My comments about icequakes were strictly in response to someone else bring the topic up as if it had the same precision and implications as Dr. Pelto’s survey of NA glaciers.

Dr. Pelto – is there a way of estimating the response time of NA glaciers to above or below average temperatures/precipitation? Would 2 or 3 cooler years in a row be sufficient or will it need a decade?